A$)$ Index into the given variable mat to extract the first row and store it into the variable row$1$

B$)$ Index into mat and extract the second column and store it into the variable col$2$

C$)$ Index into col$2$ and extract the last element store it into the variable col$2$Last

D$)$ Multiply col$2$Last and row$1$ together and store it into the variable multiplie